Filter through a table to search through foreign key table

Hi,

I'm creating an application that has many tables with many foreign key constraints. For example, in my case I have a student. Each student table has a foreign key relation with a parental details table and medical details table. 

To make my application easy to use, I have implemented a series of different filters to help a user search through large amounts of data. 

I have one listview to display the student records, and same with the parental and medical details. However, What I want to do is to search through the student records based on a set of criteria from the parental details. For example, search for a parental name. This is what Ive tried;

//Constructor;
            StudentList = new ObservableCollection<StudentViewModel>(GetStudents());

            CollectionViewSource.GetDefaultView(StudentList).Filter = new Predicate<object>(MainFilter);

        private string contactNameSearch;
        public string ContactNameSearch
        {
            get { return contactNameSearch; }
            set
            {
                contactNameSearch = value;
                CollectionViewSource.GetDefaultView(StudentList).Refresh();
                OnPropertyChanged("ContactNameSearch");
            }
        }

        private bool FilterContactNameSearch(object obj)
        {
            StudentContactViewModel item = obj as StudentContactViewModel;

            if (item == null) return false;

            if (String.IsNullOrWhiteSpace(ContactNameSearch)) return true;

            if (ContactNameSearch.Trim().Length == 0) return true;

            if (item.Name1.ToLower().Contains(ContactNameSearch.ToLower())) return true;

            return false;
        }

        public bool MainFilter(object o)
        {
            return FilterContactNameSearch(o); // &... and more filters
        }

//Within the xaml;<TextBox Height="23" Name="txtContactName" Width="100" 
                        Text="{Binding ContactNameSearch, UpdateSourceTrigger=PropertyChanged}"/>

However, when I do this, the data within student table that is populated vanishes.this link illustrates this

Therefore, my question is; Am I implementing this correctly and if not, is there an alternative way of doing it?

Thanks in advance,

Greg.